Stereoscopic endoscope system and tv imaging system for endoscope

ABSTRACT

An armor ( 111   a ) of a scope unit ( 131 ) and a diaphragm ( 123 ) are arranged to be mutually freely turnable. The shape of an outer section ( 123   c ) of the diaphragm ( 123 ) and the shape of the inside of a scope joint ( 130   a ) of a TV camera unit ( 130 ) substantially agree with each other, and the outer section ( 123   c ) of the diaphragm ( 123 ) and the inside of the scope joint ( 130   a ) engage with each other. In a state in which the outer section ( 123   c ) of the diaphragm ( 123 ) and the inside of the scope joint ( 130   a ) are engaged with each other, a ring screw ( 133 ) is meshed with a thread ( 130   b ) so that the scope unit ( 131 ) and TV camera unit ( 130 ) will unitedly be joined with each other. At this time, since the outer section ( 123   c ) of the diaphragm ( 123 ) is engaged with the scope joint ( 130   a ), the diaphragm and TV camera unit can be turned relative to an objective optical system ( 119 ) and relay optical system ( 121 ) with the optical axis of the relay optical system ( 121 ) as an axis of turning. Moreover, a liquid-crystal shutter  124  in the TV camera unit ( 130 ) has two interceptive areas ( 124   a,    124   b ) which can be switched temporally alternately. The interceptive areas ( 124   a,    124   b ) intercept one of two light beams passing through either of aperture stops ( 123   a,    123   b ).

TECHNICAL FIELD

[0001] The present invention relates to a stereoscopic endoscope systemand a TV imaging system for an endoscope which are used to observe anobject three-dimensionally.

BACKGROUND TECHNOLOGY

[0002] In recent years, endoscopes each having an elongated insertionunit thereof inserted in a body cavity for observation of an organ inthe body cavity and making it possible to use if necessary a treatmentappliance inserted in a treatment appliance channel to conduct variouscurative procedures have been adopted widely. Moreover, industrialendoscopes have been widely utilized for observation, inspection, or thelike of flaws, corrosion, or the like inside a pipe in a boiler, gasturbine, engine, chemical plant, or the like or inside a body of anautomobile engine.

[0003] The endoscopes include a flexible endoscope whose insertion unitis flexible and inserted in a curved body cavity through a mouth or thelike in order to observe or diagnose a lesion in the body cavity, and arigid endoscope whose insertion unit is rigid and inserted linearly toan intended region.

[0004] In case the flexible endoscope is of an optical type, a flexibleimage guide fiber is used as an image conveying means. The rigidendoscope has an excellent target-finding ability owing to its rigidinsertion unit, wherein a relay optical system is usually used as animage conveying means to produce an optical image.

[0005] The endoscopes including the rigid endoscope fall into a type inwhich an optical image is observed directly by naked eyes and a type inwhich an optical image picked up by a solid-state imaging device such asa charge-coupled device (CCD) serving as an imaging means is displayedin a monitor screen for observation.

[0006] With advancements in surgical procedures, endoscopic surgery, inwhich a small orifice is created in the abdomen in order to observe theabdominal cavity or conduct an operation thereon using an endoscope, isprevailing as a substitute for conventionally-adopted laparotomy. Almostall the foregoing endoscopes are designed to visualize a body cavity asa planar image that cannot give depth perception.

[0007] As far as the known endoscopes for viewing a planar image areconcerned, it is hard to observe minute irregularity on the surface of,for example, an inner wall of a body cavity which is a very importantdiagnostic indication. In an effort to overcome this drawback, astereoscopic endoscope in which optical systems are arranged in anendoscope, which is designed for producing a planar image forobservation, in such a manner that three-dimensional observation isenabled has been proposed.

[0008] The optical systems for an endoscope enabling stereoscopy fallinto three types described below.

[0009] First, a stereoscopic endoscope 10 of, as shown in FIG. 1, adual-objective dual-relay optical system type has been disclosed inJapanese Patent Laid-Open No. 6-160731. The stereoscopic endoscope 10 isconfigured by juxtaposing two identical optical systems.

[0010] In the stereoscopic endoscope 10, as shown in FIG. 1, images 13 aand 13 b formed by objective optical systems 12 a and 12 b incorporatedin a scope unit 11 are transmitted by a given distance by conveyingoptical systems 14 a and 14 b formed with systems of relay lenses. Theimages are then recomposed into parallel rays by lenses 15 a and 15 band transmitted to a TV camera unit 16.

[0011] The images transmitted to the TV camera unit 16 are formed onimaging planes of two imaging devices 18 a and 18 b by way of imageformation lenses 17 a and 17 b, whereby optical images are produced.Reference numeral d1 denotes a spacing between two optical axes that iscomparable to a parallax.

[0012] Secondly, as shown in FIG. 2, a stereoscopic endoscope 20 of asingle-objective single-relay optical system type is described inJapanese Patent Laid-Open No. 6-167658. In the stereoscopic endoscope20, a system of relay lenses serving as an objective optical system andconveying optical system is formed with a single optical system that isaxially symmetric.

[0013] In the stereoscopic endoscope 20, as shown in FIG. 2, a pair ofright and left aperture stops 23 a and 23 b and image formation lenses24 a and 24 b are located at a position 22 of image formation at theback end of the system of relay lenses 21 so that the aperture stopswill have a spacing corresponding to a parallax d2 between them. Animage is therefore spatially split into two portions. Thus, a pair ofright and left images having a parallax between them are formed on twoimaging devices 25 a and 25 b, whereby optical images are produced.

[0014] Thirdly, the present applicant has disclosed a stereoscopicendoscope 30 of a dual-objective single-relay optical system type asshown in FIG. 3 in Japanese Patent Laid-Open No. 7-261099.

[0015] In the stereoscopic endoscope 30, as shown in FIG. 3, a pair ofright and left systems of lenses are used as first groups of lenses 32 aand 32 b of an objective optical system 31 and placed so that aperturestops of the systems will have a spacing d3 between them. A second group33 of lenses of the objective optical system 31, and systems of relaylenses 34 a, 34 b, and 34 c serving as a conveying optical system areeach formed with a single optical system that is axially symmetric. Animage passing through entrance pupil formation lenses 35 located at theback end of these systems of relay lenses 34 a, 34 b, and 34 c isspatially split by aperture stops 36 a and 36 b. Resultant right andleft images are formed on two imaging devices 38 a and 38 b by a pair ofright and left image formation lenses 37 a and 37 b, whereby opticalimages are produced.

[0016] One of the advantages of the stereoscopic endoscope 10 of adual-objective dual-relay optical system type shown in FIG. 1 is that athree-dimensional image can be produced merely by juxtaposing normaloptical systems designed for an endoscope. For optimizingthree-dimensionality, the spacing dl between the optical axes ofobjective optical systems should merely be varied. In this case, theoptimization can be achieved irrespective of specifications including anangle of view. The stereoscopic endoscope of this type can be designedmore easily than the stereoscopic endoscope 20 of a single-objectivesingle-relay optical system type shown in FIG. 2.

[0017] By contrast, one of the drawbacks of the stereoscopic endoscope10 lies in that since the right and left optical systems are constructedindependently, the number of parts is large. Consequently, assembling iscomplex. Moreover, a difference in magnification between right and leftimages occurs deriving from an error of each part, and a shift of afocal point are large, and fine adjustment is required for normalstereoscopy.

[0018] One of the advantages of the stereoscopic endoscope 20 of asingle-objective single-relay optical system type shown in FIG. 2 isthat the structures of an objective optical system and system of relaylenses are identical to those of normal optical systems designed for anendoscope. Therefore, while right and left images are sharing the sameoptical path, a change of an image deriving from errors caused duringmanufacturing occurs in the right and left images in the same manner. Adifference in magnification between the right and left images and ashift of a focal point are therefore small. Moreover, since the numberof parts is small, assembling efficiency is good. When as described inJapanese Patent Laid-Open No. 6-59199, a system of relay lenses isintegrated into a scope unit and image formation lenses and imagingdevices are integrated into a TV camera unit, the orientations of imagescan be corrected by turning the units relative to each other.

[0019] On the other hand, one of the drawbacks of the stereoscopicendoscope 20 is that three-dimensionality cannot be determinedirrespective of specifications including an angle of view. The spacingbetween right and left entrance pupils of aperture stops that determinesthree-dimensionality is determined by an angle of view of an objectiveoptical system, a numerical aperture of a system of relay lenses, aspacing between the aperture stops, and the like. Normally, the diameterof an aperture stop of an objective optical system is smaller than thatof a system of relay lenses. As long as the outer diameter of aninsertion unit is identical to that of the stereoscopic endoscope 10 ofa dual-objective dual-relay optical system type shown in FIG. 1,three-dimensionality is poorer.

[0020] One of the advantages of the stereoscopic endoscope 30 of adual-objective single-relay optical system type shown in FIG. 3 is thatthree-dimensionality can be optimized irrespective to specificationsincluding an angle of view by varying the spacing d3 between opticalaxes of the two first groups of lenses of the objective optical system.Moreover, since right and left images share the same optical path in therange from the second group of lenses of the objective optical system tothe entrance pupil formation lenses, a difference in magnificationbetween the right and left images and a shift of a focal point aresmall. Besides, since the number of parts is small, assemblingefficiency is good.

[0021] By contrast, a drawback of the stereoscopic endoscope 30 lies inthat when lenses ending with the entrance pupil formation lenses areintegrated into a scope unit and lenses succeeding the entrance pupilformation lenses are integrated into a TV camera unit, the orientationsof images cannot be corrected by turning the units relative to eachother. This is because the positions of the right and left aperturestops of the scope unit are fixed by the first group of lenses of theobjective optical system. Light beams are therefore obstructed by theturning.

[0022] As mentioned above, the three typical types of stereoscopicendoscopes have both advantages and disadvantages. The endoscopes havetherefore been used selectively according to the purpose of use.

[0023] However, even in case the stereoscopic endoscopes are usedselectively according to the purpose of use, the drawbacks below occur.

[0024] In the stereoscopic endoscope 20 and stereoscopic endoscope 30,scope units that are mutually different in terms of a diameter of anaperture stop or a spacing between aperture stops; that is, in terms ofan outer diameter can be switched and coupled with one TV camera unit.

[0025] This is because that the positions of the pair of the right andleft aperture stops and the spacing between the optical axes of theimage formation lenses in the stereoscopic endoscope 20 shown in FIG. 2are fixed. Therefore, if a scope unit whose relay optical system has anaperture stop of a small diameter is mounted, light beams areobstructed. On the contrary, if a scope whose relay optical system hasan aperture stop of a large diameter is mounted, light rays that cannotbe extracted increase in number. This leads to a larger amount of wastedlight. When a plurality of scope units having different diameters areprepared and used selectively according to the purpose of use, itbecomes necessary to prepare a plurality of TV camera units in line withthe scope units. This poses a serious problem costwise.

[0026] Moreover, even if any type of TV camera unit is used, it isimpossible to replace the corresponding scope unit with any other typeof scope unit and couple it with the TV camera unit. Since the TV cameraunits are mutually incompatible, when a plurality of scope units areprepared to cope with different purposes of use, it is required toprepare a plurality of TV cameras. This poses a problem costwise.

[0027] Moreover, whichever type of TV camera unit is used, the TV cameraunit is dedicated to a stereoscopic endoscope. The TV camera unit isincompatible with the one for a rigid scope used for normal observation.

[0028] In any type of TV camera unit, the TV camera unit has a pair ofright and left image formation lenses. This leads to a large number ofparts. Moreover, since there is a difference between right and leftimages, focusing or the like is needed.

DISCLOSURE OF THE INVENTION

[0029] A stereoscopic endoscope system in accordance with the firstinvention comprises: a scope unit including at least one objectiveoptical system located in an elongated insertion unit, and at least oneconveying optical system for conveying an object image formed by theobjective optical system; and a TV camera unit including one imageformation optical system for imaging a light beam emanating from thescope unit, and an imaging device for picking up images passing throughthe image formation optical system. The stereoscopic endoscope system ischaracterized in that the scope unit and TV camera unit are detachablefrom each other, and that an image disuniting member for disuniting aplurality of images is incorporated in the TV camera unit.

[0030] According to the first invention, the image disuniting memberincorporated in the TV camera unit detachable from the scope unit candisunite a plurality of images.

[0031] A TV imaging system for an endoscope in accordance with thesecond invention comprises a scope unit having an elongated insertionunit that can be inserted in a narrow region and a TV camera unit thatcan be attached to the scope unit. The TV imaging system ischaracterized in that the TV camera unit includes a single imageformation optical system, a stop splitting member for temporallysplitting an aperture stop of the image formation optical system, and animaging device for photoelectrically transferring images formed by theimage formation optical system, and that the member for temporallysplitting the aperture stop temporally switches a state, in which one oftwo areas constituting the aperture stop of the image formation opticalsystem is transparent and the other area is interceptive, and a state inwhich the one of the two areas is interceptive and the other area istransparent.

[0032] According to the second invention, the aperture stop of the imageformation optical system can be split temporally by temporally switchingthe state, in which one of two areas constituting the aperture stop ofthe image formation optical system is transparent and the other area isinterceptive, and the state in which the one of the two areas isinterceptive and the other area is transparent.

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIGS. 1 to 3 are explanatory diagrams showing the outlineconfigurations of known scope units;

[0034]FIG. 1 is an explanatory diagram showing the configuration of adual-objective dual-relay optical system type scope unit;

[0035]FIG. 2 is an explanatory diagram showing the configuration of asingle-objective single-relay optical system type scope unit;

[0036]FIG. 3 is an explanatory diagram showing the configuration of adual-objective single-relay optical system type scope unit;

[0037] FIGS. 4 to 6 show an embodiment of the present invention;

[0038]FIG. 4 is an explanatory diagram showing the overall configurationof a stereoscopic endoscope system;

[0039]FIG. 5 are explanatory diagrams showing the configurations ofscope units of different types;

[0040]FIG. 5A is an explanatory diagram showing the configuration of asingle-objective single-relay optical system type scope unit;

[0041]FIG. 5B is an explanatory diagram showing the configuration of asingle-objective single-relay optical system type scope unit of whichinsertion unit has a smaller diameter than that of the scope unit shownin FIG. 5A;

[0042]FIG. 5C is an explanatory diagram showing the configuration of adual-objective dual-relay optical system type scope unit;

[0043]FIG. 5D is an explanatory diagram showing the configuration of adual-objective dual-relay optical system type scope unit;

[0044]FIG. 5E is an explanatory diagram showing the configuration of arigid scope used for normal observation;

[0045]FIG. 5F is an explanatory diagram showing the configuration of aTV camera unit that can be connected to the scopes shown in FIGS. 5A,5B, 5C, 5D, and 5E;

[0046]FIG. 5G is an explanatory diagram showing a liquid-crystal shutterin a TV camera unit;

[0047]FIG. 6 is an explanatory diagram showing a scope unit and TVcamera unit in a stereoscopic endoscope system;

[0048] FIGS. 7 are diagrams showing an automatic focusing mechanism in aTV camera unit in a stereoscopic endoscope system;

[0049]FIG. 7A is an explanatory diagram showing the outlineconfiguration of the automatic focusing mechanism in the TV camera unit;

[0050]FIG. 7B is a diagram showing a picked-up state of right and leftimages produced by an imaging device;

[0051] FIGS. 8 are diagrams showing the outline structure of aliquid-crystal shutter;

[0052]FIG. 8A is an explanatory diagram showing the structure of theliquid-crystal shutter;

[0053]FIG. 8B is an explanatory diagram showing two areas of theliquid-crystal shutter;

[0054] FIGS. 9 are diagrams for explaining an optical system located inthe vicinity of a junction between a scope unit and TV camera unit shownin FIG. 5A or 5B;

[0055]FIG. 9A is an explanatory diagram showing the configuration of theoptical system;

[0056]FIG. 9B is an explanatory diagram showing the positionalrelationship between aperture stops formed in a diaphragm;

[0057] FIGS. 10 are diagrams showing a shutter made using a mechanicalinterceptive plate;

[0058]FIG. 10A is an explanatory diagram showing the outlineconfiguration of the shutter made using a mechanical interceptive plate;

[0059]FIG. 10B is a diagram showing the structure of the interceptiveplate;

[0060]FIG. 11 is an explanatory diagram showing another configuration ofan optical system located in the vicinity of the junction between ascope unit and TV camera unit;.

[0061] FIGS. 12 are diagrams for explaining the scope unit that is shownin FIG. 5A or 5B and devoid of a diaphragm, and a TV camera unit;

[0062]FIG. 12A is an explanatory diagram showing the scope unit;

[0063]FIG. 12B is an explanatory diagram showing the TV camera unit;

[0064]FIG. 13 is an explanatory diagram showing the outline structure ofa liquid-crystal shutter having the capability of a diaphragm;

[0065] FIGS. 14 are diagrams for explaining examples of an electrodepattern of transparent electrodes arranged in a liquid-crystal shutter;

[0066]FIG. 14A is a diagram showing one electrode pattern of transparentelectrodes;

[0067]FIG. 14B is a diagram showing another electrode pattern oftransparent electrodes;

[0068] FIGS. 15 are diagrams for explaining examples of the state of aliquid-crystal shutter attained with application of a voltage;

[0069]FIG. 15A is a diagram showing a state in which a voltage isapplied to transparent electrodes in order to bring area a1 alone of theliquid-crystal shutter to a transparent state;

[0070]FIG. 15B is a diagram showing a state in which a voltage isapplied to the transparent electrodes in order to bring area a2 alone ofthe liquid-crystal shutter to a transparent state;

[0071] FIGS. 16 are diagrams for explaining another structure of aliquid-crystal shutter;

[0072]FIG. 16A is an explanatory diagram showing the structure of theliquid-crystal shutter which is provided with the capability of adiaphragm by means of a first aperture plate and second aperture plate;

[0073]FIG. 16B is a diagram showing the diaphragm formed with twoaperture plates from the front thereof;

[0074]FIG. 16C is an explanatory diagram showing the first apertureplate constituting the diaphragm of the liquid-crystal shutter;

[0075]FIG. 16D is an explanatory diagram showing the second aperturestop constituting the diaphragm of the liquid-crystal shutter;

[0076]FIG. 16E is a diagram showing a state in which the relativeposition of one aperture plate is changed;

[0077] FIGS. 17 are diagrams for explaining another configuration of aTV camera unit;

[0078]FIG. 17A is an explanatory diagram showing the configuration of aTV camera unit in which polarizing plates permitting mutuallyperpendicular polarizing directions;

[0079]FIG. 17B is a diagram showing the structure of a polarizing plate;

[0080] FIGS. 18 are diagrams showing another configuration of a TVcamera unit;

[0081]FIG. 18A is an explanatory diagram showing the configuration of aTV camera unit in which a slit type polarizing plate is placed on thefront side of an imaging device on behalf of a deflection beam splitter;

[0082]FIG. 18B is a diagram showing the structure of a polarizing plate;

[0083]FIG. 18C is a diagram showing an example of the structure of aslit type polarizing plate;

[0084]FIG. 18D is a diagram showing another example of the structure ofthe slit type polarizing plate;

[0085]FIGS. 19 and 20 are diagrams for explaining a rigid scope in whichone scope unit includes two observation optical systems permittingdifferent field-of-view directions;

[0086] FIGS. 19 are diagrams for explaining a scope unit in whichoptical systems are juxtaposed;

[0087]FIG. 19A is an explanatory diagram showing the configuration of ascope unit;

[0088]FIG. 19B is an explanatory diagram showing a TV camera unit to beconnected to the scope unit shown in FIG. 19A;

[0089]FIG. 19C is a diagram showing split areas of an aperture stop inthe TV camera unit shown in FIG. 19B;

[0090] FIGS. 20 are diagrams for explaining a scope unit in which twosets of a single objective optical system and single relay opticalsystem are juxtaposed;

[0091]FIG. 20A is an explanatory diagram showing the configuration ofthe scope unit;

[0092]FIG. 20B is an explanatory diagram showing a TV camera unit to beconnected to the scope unit shown in FIG. 20A;

[0093]FIG. 20C includes diagrams showing split areas of an aperture stopin the TV camera unit shown in FIG. 20B;

[0094]FIG. 20D is an explanatory diagram showing the configuration of aTV camera unit including a polarizing plate; and

[0095]FIG. 20E is a diagram showing split areas of the polarizing plate.

BEST MODES FOR CARRYING OUT THE INVENTION

[0096] Referring to the drawings, embodiments of the present inventionwill be described below.

[0097] Referring to FIGS. 4 to 6, the first embodiment of the presentinvention will be described.

[0098] As shown in FIG. 4, a stereoscopic endoscope system 101comprises: a stereoscopic endoscope 102 including an imaging opticalsystem and illumination optical system used for stereoscopy; a lightguide 103 serving as an illumination light conveying means lying throughthe stereoscopic endoscope 102; a light source apparatus 104 including,for example, a lamp 104 a for generating illumination light of whitelight and thus supplying the illumination light, and a lens 104 b forconverging the white light; a camera control unit 106 (hereinafter a CCU106) for processing electric signals sent from an imaging device 105serving as an imaging means incorporated in the stereoscopic endoscope102; a scan converter 107 for converting signals output from the CCU 106into video signals; a color monitor 108 for displaying video signalsoutput from the scan converter 107; shutter glasses 109 having thecapability of a shutter for three-dimensionally discerning imagesdisplayed on the color monitor 108; and a face-mounted display 110(hereinafter an FMD 110) to be worn by an operator in order tothree-dimensionally discern signals output from the CCU 106.

[0099] The stereoscopic endoscope 102 includes an elongated insertionunit 111 to be inserted in a body cavity, and a grip unit 112 located atthe back end of the insertion unit 111 and to be gripped by an operator.The insertion unit 111 is formed with an armor 111 a that is shaped likea round pipe and that is realized with a rigid metallic member made ofstainless steel or the like. In short, the stereoscopic endoscope 102 isa so-called rigid scope having the rigid insertion unit 111.

[0100] The insertion unit 111 includes, similarly to that of anelectronic endoscope intended to produce a planar image for normalobservation, a light guide 103 for conveying illumination light suppliedfrom the light source apparatus 104, and an illumination optical systemfor irradiating illumination light conveyed by the light guide 103through an illumination window 113 so as to illuminate an object 114.Moreover, an observation optical system, which will be described later,for producing two views having a parallax between them is included sothat the object 114 illuminated by the illumination optical system canbe visualized stereoscopically. In this specification, an optical systemhaving the operation of forming two images, which have a parallaxbetween them, on an imaging device having a photoelectric transferfunction is used as the observation optical system. The observationoptical system is therefore also referred to as an imaging opticalsystem.

[0101] The grip unit 112 has a light guide base 115 to which the backend of the light guide 103 is jointed. One end of a light guide cable116 is connected to the light guide base 115 so that the light guidecable 116 can be detached freely. A light guide connector 116 a isattached to the other end of the light guide cable 116, whereby thelight guide cable 116 is connected freely detachably to the light sourceapparatus 104. When the light source apparatus 104 and light guide base115 are linked by the light guide cable 116, the white light emanatingfrom the lamp 104 a is converged by the lens 104 b, and irradiated tothe end side of the light guide connector 116 a. The white lightirradiated to the end side is supplied to the light guide 103 by way ofthe light guide cable 116 and light guide base 115. The light guide 103is angled inside the grip unit 112 and passed through the insertionunit. The illumination light supplied to the light guide 103 isirradiated through the illumination window 113 formed in a distalsection 117 of the insertion unit 111.

[0102] Now, an observation optical system will be described withreference to FIG. 5A.

[0103] An optical image 120 of the object 114 illuminated byillumination light is formed at a position of image formation by anobjective optical system 119 constituting a single-objectivesingle-relay optical system type observation optical system opposed toan observation window 118 adjoining the illumination window 113 of thedistal section 117 as shown in FIGS. 4 and 5A. The optical image 120 isconveyed to the back end of the insertion unit 111 by a relay opticalsystem 121. A light beam representing a last image 122 transmitted bythe relay optical system 121 is halved by a diaphragm 123 havingaperture stops 123 a and 123 b that are formed mutually separately.

[0104] The halved light beams are alternately intercepted by a a meansfor temporally disuniting a plurality of images, for example, aliquid-crystal shutter 124, and finally formed on an image formationplane of the imaging device 105, which is a photoelectric transferplane, through image formation lenses 125. As shown in FIG. 4, the shapeof the imaging plane of the imaging device 105 is, for example, asquare. The imaging device 105 is placed so that lengthwise or sidewaysdirection of the imaging plane of the imaging device 105 will coincidewith the lateral direction of the two aperture stops 123 a and 123 bwhich are formed mutually separately.

[0105] The grip unit 112 constitutes a TV camera unit 130 in which theliquid-crystal shutter 124 for temporally disuniting images, imageformation lenses 125, and imaging device 105 are incorporated. Theinsertion unit 111 constitutes a scope unit 131 including the lightguide 103, illumination window 113, observation window 118, objectiveoptical system 119, and relay optical system 121.

[0106] As shown in FIGS. 5F and 6, the armor 111 a of the scope unit 131and the diaphragm 123 are designed to be freely turnable. The shape ofan outer section 123 c of the diaphragm 123 and the shape of the insideof a scope joint 130 a of the TV camera unit 130 substantially agreewith each other, and the outer section 123 c and the inside of the scopejoint 130 a engage with each other. In a state in which the outersection 123 c of the diaphragm 123 and the inside of the scope joint 130a of the TV camera unit 130 are engaged with each other, a ring screw133 mounted on the scope unit 131 is meshed with a thread 130 b formedon the TV camera unit 130. Thus, the diaphragm 123 and TV camera unit130; that is, the scope unit 131 and TV camera unit 130 are unitedlyjoined with each other.

[0107] At this time, since the outer section 123 c of the diaphragm 123is engaged with the scope joint 130 a of the TV camera unit 130, thediaphragm and TV camera unit can be turned relative to the objectiveoptical system 119 and relay optical system 121 with the optical axis ofthe relay optical system 121 as an axis of turning.

[0108] As shown in FIG. 5G, the liquid-crystal shutter 124 in the TVcamera unit 130 has two interceptive areas 124 a and 124 b which areswitched temporally alternately. The interceptive areas 124 a and 124 bare defined to intercept one of two light beams passing through eitherof the aperture stops 123 a and 123 b.

[0109] The imaging device 105 and CCU 106 are linked by a signal cable132 extending from the back end of the TV camera unit 130. Electricsignals produced by photoelectrically transferring images that aretemporally disunited while passing through the two aperture stops 123 aand 123 b and that are then formed on the imaging device 105 areprocessed into image signals by the CCU 106. The image signals areoutput to the scan converter 107, converted into video signals, and thenoutput to the color monitor 108. At this time, images passing throughthe two aperture stops 123 a and 123 b and having a parallax betweenthem are displayed on the color monitor 108 on a time-sharing basis. Theimages displayed on the color monitor 108 are observed by an operatorvia the shutter glasses 109 or observed through the FMD 110 worn by theoperator. Thus, the object 114 can be discerned three-dimensionally.

[0110] Now, the scope unit 131 will be described with reference to FIGS.5.

[0111]FIG. 5A shows a single-objective single-relay optical system typescope unit 131 a. In the scope unit 131 a, an objective optical system119, relay optical system 121, and diaphragm 123 are arranged in thatorder from the object side. An optical image 120 formed by the objectiveoptical system 119 is conveyed to the proximal side by the relay opticalsystem 121. A light beam representing a last image 122 conveyed by therelay optical system 121 is split by a diaphragm 123, and emitted fromthe scope unit 131 a to a TV camera unit 130 engaged with and connectedto an outer section 123 c of the diaphragm 123. The diaphragm 123 hastwo aperture stops 123 a and 123 b, and is placed to be axiallysymmetric with respect to the optical axis of the relay optical system121. Three-dimensionality, brightness, or the like can be optimized byadjusting the spacing between the two aperture stops 123 a and 123 b andthe diameter of each of them. A direction Y in which the aperture stops123 a and 123 b are separated from each other, and a direction X of aborder between two interceptive areas 124 a and 125 b of aliquid-crystal shutter 124 are substantially orthogonal to each other.Images of the aperture stops formed in the image space are so-calledexit pupils.

[0112] By contrast, FIG. 5B shows a single-objective single-relayoptical system type scope unit 131 b that resembles the one shown inFIG. 5A but that has a smaller outer diameter than the one shown in FIG.5A. The spacing between two aperture stops 123 a and 123 b of the scopeunit 131 b is narrower than the one shown in FIG. 5A. However, the outersection 123 c of the diaphragm 123 of the scope unit 131 b has the sameshape as the one in FIG. 5A. The TV camera unit 130 can therefore beconnected to the scope unit 131 b. At this time, a direction Y in whichthe two aperture stops 123 a and 123 b are separated from each other,and a direction X of a border between the two interceptive areas of theliquid-crystal shutter 124 are substantially perpendicular to eachother. Besides, the two aperture stops 123 a and 123 b are arranged tobe axially symmetric with respect to a border 124 c. Even if the spacingbetween the two aperture stops 123 a and 123 b is varied, since a fieldof view will not be obstructed, imaging can be achieved. Aside from theouter diameter, the components are identical to those shown in FIG. 5A.

[0113] By contrast, FIG. 5C shows a dual-object dual-relay opticalsystem type scope unit 131 c in which two optical system each having thesame components as the one shown in FIG. 5B are arranged in parallel.Optical images 120 a and 120 b formed by objective optical systems 119 aand 119 b are conveyed to the proximal side as last images 122 a and 122b by relay optical systems 121 a and 121 b, recomposed intosubstantially parallel rays by lenses 135 a and 135 b, and then emittedfrom the scope unit 131 c to the TV camera unit 130 engaged with andconnected to the outer section 123 c of the diaphragm 123.

[0114] At this time, when the scope unit 131 c and TV camera unit 130are turned, since the scope unit 131 c is of a dual-objective dual-relayoptical system type, aperture stops 136 a and 136 b located at theoutput end of the scope unit and the liquid-crystal shutter 124 in theTV camera unit 130 are turned relative to each other. In this state,light beams passing through the two aperture stops 136 a and 136 bcannot be intercepted alternately. The scope unit 131 c and TV cameraunit 130 may therefore be screwed to and fixed to each other so thatthey cannot be turned relative to each other. For enabling both theunits to make a relative turn, the interceptive areas 124 a and 124 b ofthe liquid-crystal shutter 124 is made mechanically or electricallyturnable together with the scope unit 131 c.

[0115] The aperture stops 136 a and 136 b of the scope unit 131 c aredefined by right and left lenses 135 a and 135 b. The diaphragm 123 maynot have aperture stops but may have a mere opening.

[0116]FIGS. 5D shows a dual-objective single-relay optical system typescope unit 131 d. The objective optical system 119 having two separateobjective-side aperture stops, the relay optical system 121, and anentrance pupil formation lens 137 are arranged in that order from theobject side. The objective optical system 119 comprises first opticalsystems 138 a and 138 b that are juxtaposed with the optical axesthereof separated from each other and that have the same configuration,and a second optical system 139 placed in order to integrate the opticalaxes into one optical axis. Two optical images 120 a and 120 b having aparallax between them are formed at positions that are spatiallysubstantially coincident with each other. The optical images 120 a and120 b are relayed to the proximal side by the relay optical system 121with the sizes thereof unchanged. The optical images are then recomposedinto substantially parallel rays by the entrance pupil formation lens137, and then emitted from the scope unit 131 d to the TV camera unit130 engaged with and connected to the outer section 123 c of thediaphragm 123.

[0117] At this time, similarly to FIG. 5C, if the scope unit 131 d andTV camera unit 130 are turned relative to each other, aperture stops 140a and 140 b of the scope unit 131 d and the liquid-crystal shutter 124in the TV camera unit 130 are turned relative to each other. Light beamspassing through the two aperture stops 140 a and 140 b cannot thereforebe intercepted alternately. The scope unit 131 d and TV camera unit 130may therefore be screwed to and fixed to each other so that both theunits cannot be turned relative to each other. For enabling both theunits to make a relative turn, the interceptive areas 124 a and 124 b ofthe liquid-crystal shutter 124 are made mechanically or electricallyturnable together with the scope unit 131 d. The aperture stops 140 aand 140 b are defined by the first optical systems 138 a and 138 blocated at the distal end. The diaphragm 123 may therefore not haveaperture stops but may have a mere opening.

[0118]FIG. 5E shows a scope unit 131 e for a rigid scope used for normalobservation through a planar image. An optical image 120 formed by theobjective optical system 119 is conveyed to the proximal side by therelay optical system 121, recomposed into substantially parallel rays bya lens 141, and then emitted from the scope unit 131 e to the TV cameraunit 130 engaged with and connected to the outer section 123 c of thediaphragm 123.

[0119] When the TV camera unit 130 is connected to the scope unit 131 efor a rigid scope, the liquid-crystal shutter 124 is not actuated butthe interceptive areas 124 a and 124 b are opened. Alternatively, whenthe liquid-crystal shutter 124 must be actuated, either of right andleft images is displayed and thus a normal view is produced. In thisrigid scope, the scope unit 131 e and TV camera unit 130 can be turnedrelative to each other with respect to the optical axis of the relayoptical system 121.

[0120] Moreover, even when the scope unit 131 e for a rigid scope isused, if it is connected to the TV camera unit 130, the scope unit canenable stereoscopic observation similarly to any other scope unit. Inother words, two portions of a single light beam emitted substantiallyin parallel from the lens 141 that is an eyepiece lens for an ordinaryrigid scope are intercepted alternately by a means for temporallysplitting an aperture stop, for example, a liquid-crystal shutter or amechanical rotary interceptive plate, which is located in the TV cameraunit 130. This results in right and left images having a parallaxbetween them.

[0121] Specifically, since the outer sections 123 c of the diaphragms123 serving as engaging sections enabling engagement with the TV cameraunit 130 in the scope units 131 a, 131 b, 131 c, 131 d, and 131 e sharethe same shape, the one TV camera unit 130 can be coupled with any ofthe scope units 131 a, 131 b, 131 c, 131 d, and 131 e.

[0122] As mentioned above, when outer sections of diaphragms in aplurality of scope units are shaped to engage with the inside of a scopejoint in one TV camera unit, the TV camera unit can be made freelyattachable to the plurality of scope units. Even if an imaging devicethat will be used more frequently should break down, it can be repairedor replaced with a new one readily. Moreover, a high-sensitivity TVcamera unit or high-resolution TV camera unit having an imaging devicewith a large number of pixels can be made compatible with scope unitsthat are different from one another in terms of a field-of-viewdirection, an angle of visibility, three-dimensionality, or an outerdiameter. Moreover, when the TV camera unit is made turnable withrespect to the optical axis of a relay optical system in the scope unitin a state in which the scope unit and TV camera unit are attached toeach other, it becomes possible to correct orientations of images.

[0123] Moreover, a TV camera unit uses one image formation opticalsystem to form a plurality of object images, which have a parallaxbetween them, on an imaging means, and the outer sections of diaphragmsof a plurality of scope units are shaped to engage with the inside of ascope joint of the one TV camera unit. Consequently, even if a scopeunit whose aperture stops have a different diameter or a differentspacing between them is attached, observation can be achieved withoutobstruction of light beams. When the size of an aperture stop in animage formation optical system is set in line with the largest diameterof aperture stops or the largest spacing between them among alldiameters or spacings of or between aperture stops of scope unitsemployed, whichever one of the scope units is used, emitted light can beefficiently used for image formation by the image formation opticalsystem without any leakage.

[0124] Furthermore, since one image formation optical system is employedin a TV camera unit, an optical system for forming two images having aparallax between them is shared by right and left images. A variation ofan image deriving from errors caused during manufacturing thereforeoccurs in common between the right and left images. There can thereforebe provided a TV camera unit characterized by a small error inmagnification between the right and left images, a small shift of afocal point, and improved assembling efficiency due to a small number ofparts.

[0125] Incidentally, the image formation lenses 125 in the TV cameraunit 130 may be, for example, a variable-power optical system such as azoom lens, so that observation can be achieved by enlarging or reducinga picture size in compliance with the different sizes of the last images122, 122 a, and 122 b of the scope units. At this time, it isrecommended that the variable power should range from about 1.5 to 5 andthat the image formation lenses 125 should be made movable in an axialdirection in order to enable focusing. Moreover, for a more compactdesign, an aspherical lens, bending rate distributed type lens,diffraction type lens device, or the like may be used.

[0126] Furthermore, focusing a TV camera unit may be automated. In thiscase, as shown in FIG. 7A, a motor Al used to move the image formationlenses 125 in an axial direction is incorporated in the TV camera unit.Driving force given by the motor 171 is conveyed to a moving unit 172formed with a cam or gear in order to move the image formation lenses125. As shown in FIG. 7B, electric signals representing the producedright and left images 105R and 105L are processed into image signals bythe CCU 106. At this time, luminance signals concerning substantiallythe centers of the right and left images 105R and 105L are used andprocessed, whereby a mismatch between the centers of the right and leftimages on the CCD 105 is detected. Based on the mismatch, the CCU 106outputs a driving signal to the monitor 171 so as to move the imageformation lenses 125. Driving the image formation lenses 125 by means ofthe motor 171 is continued until the mismatch is judged to be zero.

[0127] Referring to FIGS. 8, the structure of the liquid-crystal shutter124 will be described.

[0128] As shown in FIG. 8A, the liquid-crystal shutter 124 comprises twopolarizing plates 145 a and 145 b, two transparent substrates 146 a and146 b, transparent electrodes 147 a and 147 b formed on the substrates,a liquid-crystal layer 148, and a sealant 149 used to retain thethickness of the liquid-crystal layer 148 at a constant level and lockthe liquid crystal at the same time. As for a driving method for theliquid crystal, any of field effect, dynamic scattering, and thermaleffect techniques can be employed. A twisted nematic mode (hereinafter aTN mode) based on the field effect technique is most generally adoptedand easy to use.

[0129] As shown in FIG. 8A, each of the transparent electrode 147 a onthe substrate 146 a and the transparent electrode 147 b on the substrate146 b, which are located at both edges, is divided into two areas 124 aand 124 b. A voltage is applied alternately to the two areas. Thus, asshown in FIG. 8B, the two areas 124 a and 124 b can be interceptedalternately.

[0130] The transmittance attained when the liquid-crystal shutter 124 isintercepted is dependent on an angle of incidence of light. The largerthe angle of incidence of light is, the higher the transmittance is. Ashutter effect gets weaker. It is therefore recommended that the angleof incidence of light to the liquid-crystal shutter 124 be 20° atmaximum, or if possible, at 10° or lower.

[0131] Moreover, as shown in FIGS. 9A and 9B, as far as the opticalsystem located in the vicinity of the junction between the scope unitand TV camera unit which is shown in FIG. 5A or 5B is concerned,assuming that the height of the last image 122 produced by a last relaylens 121 e is h, the distance of the diaphragm 123 from the last image122 is L, the diameter of the aperture stops 123 a and 123 b is ø, andthe spacing between the aperture stops 123 a and 123 b is d, the maximumvalue θ of an angle of incidence of light to the liquid-crystal shutter124 is expressed as follows:

θ=tan⁻¹ {[h+(d+ø)/2]/L}

[0132] By contrast, in the scope unit shown in FIG. 5D or 5E, as lens137 is, as shown in FIG. 11, placed behind the last image 122 producedby the last relay lens 121 e. Substantially parallel rays are thusemitted from the scope unit 131. In this case, assuming that the heightof the last image 122 produced by the last relay lens 121 e is h and thefocal length of the lens 137 is f, the maximum value θ of the angle ofincidence of light to the liquid-crystal shutter 125 is expressed asfollows:

θ=tan⁻¹(h/f)

[0133] Consequently, the respective parameters should be determined onthe assumption that a maximum angle of incident of light to theliquid-crystal shutter 124 is set to 20°, or if possible, 10° or lower.

[0134] Incidentally, a mechanical interceptive plate may be substitutedfor the liquid-crystal shutter 124 for temporally disuniting a pluralityof images. That is to say, as shown in FIG. 10A, when the mechanicalinterceptive plate is used to constitute a shutter 175, for example, around interceptive plate 176 is rotated by means of a motor 177. Sincethe interceptive plate 176 has, as shown in FIG. 10B, two apertures 176a and 176 b, light beams passing through two apertures 123 a and 123 bformed in a diaphragm 123 shown in FIG. 10A are intercepted alternately.Alternatively, an electro-chromic device utilizing electrochemicalreaction, an electrophoretic interceptive device utilizingelectro-deposition of colored colloidal particles, or the like will do.

[0135] Moreover, an infrared cutoff filter, laser beam cutoff filter,color correction filter, or the like may be incorporated in the TVcamera unit 130 if necessary. For a more compact design, it is desiredthat the filters are united with the liquid-crystal shutter 124 orintegrated into one common filter. For example, a method of coating thepolarizing plates 145 or transparent substrates 146 constituting theliquid-crystal shutter 124 with a coherent membrane effective forcutting off a laser beam, or a method of using an infrared cutoff filteror color correction filter as the transparent substrates 146 isconvenient.

[0136] Furthermore, various kinds of solid-state imaging devicesgenerally known by the names of a CCD, PCD, CMD, AMI, SIT, and the like,or image pickup tubes generally known by the names of Saticon, Vidicon,a HARP tube, and the like may be used as the imaging device 105 in theTV camera unit 130. An image intensifier or the like may be used toimprove sensitivity.

[0137] The imaging device may be of a type in which a single-platetechnique is used for color imaging or of a type in which the imagingdevice is formed as a dual-plate or triple-plate camera for colorimaging. Moreover, the imaging device 105 may be incorporated unitedlyin the TV camera unit 130, or may be formed as a separate unit so thatit can be replaced with a new one.

[0138] The stereoscopic endoscope system 101 adopts a simultaneousillumination and imaging method in which the imaging device 105 having acolor separation filter such as a mosaic filter is used to achieve colorimaging under the illumination of white light. The present invention isnot limited to this method, but may apply to a field sequential imagingmethod in which the imaging device 105 not having a color separationfilter is used to produce color component images of three elementarycolors under the field-sequential illumination of different kinds ofillumination light that have wavelengths of red, green, and blue andthat are emitted sequentially to an object.

[0139] The liquid-crystal shutter is not limited to the aforesaidstructure but may be structured as described below.

[0140] As shown in FIGS. 12, when a diaphragm is not placed in the scopeunit 131 shown in FIGS. 5A or 5B, a liquid-crystal shutter 124A placedin the TV camera unit 130 is provided with the capability of a diaphragmin addition to the capability of a shutter. Specifically, as shown inFIG. 13, the liquid-crystal shutter 124A has basically the samestructure as the liquid-crystal shutter 124 shown in FIG. 8. However,transparent substrates 150 a and 150 b, and transparent electrodes 151 aand 151 b located on the transparent substrates 150 a and 150 b areadditionally mounted one by one on both the sides of the liquid-crystallayer 148.

[0141] As shown in FIGS. 14A and 14B, the transparent electrodes 147 aand 147 b located outside are used to control a diaphragm, and thetransparent electrodes 151 a and 151 b located inside are used tocontrol a shutter.

[0142] To be more specific, when a voltage is applied to theliquid-crystal shutter 124A, as shown in FIGS. 15, if the polarizingdirections permitted by the two polarizing plates 145 a and 145 b arematched in TN mode, the polarizing direction of light permitted by aportion of the liquid-crystal shutter to which the voltage is applieddoes not vary. This means that light is not intercepted by the portion.On the contrary, the polarizing direction permitted by a portion of theliquid-crystal shutter to which the voltage is not applied is turned90°. Light is therefore intercepted. Consequently, when a constantvoltage that is slightly lower than a threshold voltage is applied toelectrode A and a pulsating voltage is applied to electrodes a1 and a2,portions of the liquid-crystal shutter in which electrode A andelectrodes a1 and a2 overlap each other constitute a shutter.

[0143] Moreover, a liquid-crystal shutter 124B shown in FIG. 16A isdesigned to implement the capability of a diaphragm in the TV cameraunit 130. As shown in FIG. 16B, the liquid-crystal shutter 124B is madeby placing a first mechanical aperture plate 152 shown in FIG. 16C and asecond aperture plate 153 shown in FIG. 16D on the front side of theliquid-crystal shutter 124. In the first aperture plate 152, forexample, two sets of apertures 154 a and 154 b, and 155 a and 155 b areformed axially symmetrically. In the second aperture plate 153,apertures 153 a and 153 b are formed with a given diameter and spacing.The capability of a diaphragm given by the liquid-crystal shutter 124Bis implemented by turning the first aperture plate 152 relative to thesecond aperture plate 153 that is stationary. Thus, aperture stopssuitable for each scope unit can be selected.

[0144] Next, a means for disuniting a plurality of images having aparallax between them in a TV camera unit on the basis of polarizationwill be described.

[0145] As shown in FIG. 17A, a TV camera unit 156 of this embodiment hasa polarizing plate 157 that consists of areas 157 a and 157 b permittingpolarizing directions that are, as shown in FIG. 17B, mutuallyperpendicular. Light beams passing through the polarizing plate 157 andrepresenting right and left images are recomposed into converged lightby image formation lenses 125. The converged light is then split intolight beams representing the right and left images by a polarizationbeam splitter 158, and formed on the imaging planes of imaging devices105 a and 105 b located separately. Thus, a three-dimensional image canbe discerned.

[0146] The other components are identical to those of the aforesaidembodiment. A scope unit 131 to be coupled with the TV camera unit 156has the same configuration as any of those shown in FIGS. 5. The shapesof the engagement sections of the TV camera units and scope unit 131 areidentical to those shown in FIG. 5.

[0147] The polarizing plate 157 in the TV camera unit includes two areas157 a and 157 b permitting mutually-perpendicular polarizing directions.The polarizing areas are arranged so that only one of two light beamsbeing emitted from the scope unit 131 and passing through aperture stops(123 a and 123 b, 136 a and 136 b, or 140 a and 140 b) will betransmitted by one of the polarizing areas. A direction X in which thetwo aperture stops are separated from each other and a direction Y of aborder between the two polarizing areas 157 a and 157 b of thepolarizing plate are substantially orthogonal to each other.

[0148]FIG. 18A shows a variant of the embodiment shown in FIG. 17. Aplurality of slit-type polarizing plates 159 which permitmutually-orthogonal polarizing directions are, as shown in FIG. 18C or18D, mounted alternately on the front side of an imaging device 105instead of the polarization beam splitter 158 to be included in the TVcamera unit 156. Specifically, the two polarizing directions permittedby the slit-type polarizing plates 159 and the two polarizing directionspermitted by the polarizing plate 157 agree with each other. Right andleft images are formed alternately in a slit-like form on the imagingplane of the imaging device 105. Electric signals representing the rightand left images formed on the imaging plane of the imaging device areprocessed and displayed separately, whereby a three-dimensional imagecan be discerned.

[0149] In FIGS. 19 and 20, two observation optical systems permittingdifferent field-of-view directions are incorporated in one scope unit131 f or 131 g. Even these scope units 131 f and 131 g have outersections 123 c of diaphragms 123 thereof shaped like those in theaforesaid embodiments so that the scope units can be coupled with a TVcamera unit 130 of a stereoscopic endoscope system 101.

[0150] Specifically, as shown in FIG. 19A, this rigid scope has twoobservation optical systems permitting different field-of-viewdirections arranged in parallel in an insertion unit. In other words,last images 122 a and 122 b, which are entrance pupils of aperture stops136 a and 136 b of the scope unit 131 f, can be disunited on a temporalbasis or on the basis of polarization and then picked up by means of theTV camera unit 130 shown in FIG. 19B.

[0151] By contrast, in FIG. 20A, two stereoscopic endoscope observationoptical systems of a single-objective single-relay optical system typewhich permit different field-of-view directions are arranged inparallel. In other words, it is made possible that last images, whichare entrance pupils of four aperture stops of the scope unit 131 g;right and left aperture stops 123 a and 123 b associated with adirect-view direction and right and left aperture stops 123 d and 123 eassociated an oblique-view direction, are disunited on a temporal basisor on the basis of polarization by means of a TV camera unit 130 shownin FIG. 20B.

[0152] Specifically, for disuniting the entrance pupils temporally, fourareas 160 a, 160 b, 160 c, and 160 d as shown in FIG. 20 are regarded asentrance pupil separation areas. Right and left images emanating fromthe direct-view direction are acquired through the areas 160 a and 160b, and right and left images emanating from the oblique-view directionare acquired through the areas 160 c and 160 d.

[0153] For disuniting the entrance pupils on the basis of polarization,a polarizing plate 161 is, as shown in FIG. 20D, placed in the TV cameraunit 156 shown in FIG. 17. The polarizing plate 161 is used to specifythe entrance pupils emanating from one of the field-of-view directions.Thereafter, a polarizing plate 157 and polarization beam splitter 158are used to disunite the entrance pupils into light beams representingright and left images. The right and left images are formed on theimaging planes of imaging devices 105 a and 105 b located independently,whereby a three-dimensional image can be discerned. The polarizing plate161 may be a mechanically rotatable plate or a plate that is formedusing a liquid crystal or the like and designed to intercept lightelectrically.

[0154] For displaying images emanating from two field-of-view directionsof the direct-view and oblique-view directions on a monitor, the imagesmay be switched if necessary and displayed in a screen on one monitor.Alternatively, the screen on a monitor may be divided into a pluralityof areas and the images may be displayed in the areas at a time.Otherwise, the images may be displayed separately on two monitors.

[0155] As described so far, according to the present invention, oneimage formation optical system is used to form a plurality of objectimages having a parallax between them on an imaging means. If anaperture stop of the image formation optical system is made sufficientlylarge, when scope units which are mutually different in a diameter of anaperture stop or a spacing between aperture stops are attached to one TVcamera unit, observation can be achieved without obstruction of lightbeams.

[0156] To be more specific, the size of an aperture stop of an imageformation optical system is set to agree with the largest diameter of anaperture stop or the largest spacing between aperture stops of alldiameters or spacings provided by scope units employed. Thus, whicheverone of the scope units is employed, emitted light can be utilized forimage formation by the image formation optical system without a leakage.

[0157] Moreover, for sequentially picking up a plurality of imageshaving a parallax between them, a shutter or the like should be includedas a means for alternately switching transmission and interception on atime-sharing basis relative to different areas or halves of an aperturestop of an image formation optical system. A combination of polarizingfilters may be included as a means for transmitting mutually-differentpolarized components relative to different areas of the aperture stop ofthe image formation optical system in place of the above means.Furthermore, a means for selectively transmitting the differentpolarized components may be placed on the incident side of an imagingdevice. In these cases, it is desired that the size of each aperturestop of a scope unit should substantially be agreed with that of theaperture stop of the image formation optical system. It is also desiredthat the switching means or the means for transmitting polarized lightbe placed at a position of image formation or in the vicinity of theposition.

[0158] Furthermore, when a TV camera unit in accordance with thisembodiment is employed in a rigid scope used for normal observation butnot designed for stereoscopy, a means for producing a plurality ofimages having a parallax between them is not actuated. If the means isactuated, one of right and left images is not displayed. When it saysthat the means is not actuated, the following mode is conceivable: whena means for switching a plurality of images on a time-sharing basis is ameans for switching passage and interception such as a shutter, themeans is set in a full-surface transparent state. When an amount oflight emitted from a scope unit is sufficiently large, the means may beretained in a partly-transparent state or partly-interceptive state.

[0159] One image formation optical system is employed in a TV cameraunit in accordance with the present invention. An optical system forforming two images having a parallax between them is shared by right andleft images. A variation of an image deriving from errors caused duringmanufacturing occurs in both the right and left images in the samemanner. An error in magnification between the right and left images anda shift of a focal point are therefore small. Moreover, since the numberof parts is small, assembling efficiency is better.

[0160] In the present invention, it will be apparent that a wide rangeof different embodiments can be formed on the basis of the inventionwithout any departure from the spirit or scope of the invention. Thisinvention will be limited to the appended claims but not restricted toany specific embodiments.

AVAILABILITY IN INDUSTRY

[0161] As described so far, according to the present invention, astereoscopic endoscope system comprises a scope unit including at leastone objective optical system, and a TV camera unit including one imageformation optical system for imaging a light beam emanating from thescope unit, and an imaging device for picking up images passing throughthe image formation optical system. The scope unit and TV camera unitare detachable from each other, and an image disuniting meansincorporated in the TV camera unit can disunite a plurality of images. ATV imaging system for an endoscope comprises a scope unit having aninsertion unit and a TV camera unit that can be attached to the scopeunit. The TV camera unit includes a single image formation opticalsystem, a stop splitting member for temporally splitting an aperturestop of the image formation optical system, and an imaging device forphotoelectrically transferring images formed by the image formationoptical system, and can disunite a plurality of images by temporallyswitching a state, in which one of two areas constituting the aperturestop of the image formation optical system is transparent and the otherarea is interceptive, and a state in which the one of the two areas isinterceptive and the other area is transparent.

What is claimed is:
 1. A stereoscopic endoscope system, comprising: ascope unit including at least one objective optical system located in anelongated insertion unit and at least one conveying optical system forconveying an object image produced by said objective optical system; anda TV camera unit including one image formation optical system forimaging a light beam emitted from said scope unit and an imaging meansfor picking up images passing through said image formation opticalsystem, wherein: said scope unit and said TV camera unit are freelydetachable from each other, and an image disuniting means for disunitinga plurality of images is incorporated in said TV camera unit.
 2. Astereoscopic endoscope system according to claim 1 , wherein said scopeunit and said TV camera unit are freely attachable to each other byengaging a scope joint formed in said TV camera unit with an outersection of a diaphragm located on said scope unit.
 3. A stereoscopicendoscope system according to claim 1 , wherein said image disunitingmeans for disuniting a plurality of images which is located in said TVcamera unit is a means for disuniting images on a temporal basis.
 4. Astereoscopic endoscope system according to claim 1 , wherein said imagedisuniting means for disuniting a plurality of images which is locatedin said TV camera unit is a means for disuniting images on the basis ofpolarization.
 5. A stereoscopic endoscope system according to claim 1 ,wherein a diaphragm having a plurality of apertures or a plurality ofaperture stops are located in said scope unit.
 6. A stereoscopicendoscope system according to claim 1 , wherein a diaphragm having aplurality of apertures is located in said TV camera unit.
 7. Astereoscopic endoscope system according to claim 1 , wherein a pluralityof scope units that are mutually different in terms of at least one ofan outer diameter, an angle of field, a diameter of an aperture stop, aspacing between aperture stops, and a type of stereoscopic endoscopeoptical system are freely attachable to one TV camera unit includingsaid image disuniting means for disuniting a plurality of images andsaid one image formation optical system.
 8. A stereoscopic endoscopesystem according to claim 3 , wherein said means for disuniting aplurality of images on a temporal basis is a liquid-crystal shutter. 9.A stereoscopic endoscope system according to claim 4 , wherein saidmeans for disuniting a plurality of images on the basis of polarizationis a combination of a polarizing plate and polarization beam splitter.10. A stereoscopic endoscope system according to claim 4 , wherein saidmeans for disuniting a plurality of images on the basis of polarizationis a combination of a polarizing plate and slit-type polarizing plates.11. A stereoscopic endoscope system according to claim 3 or 4 , whereinsaid image formation optical system in said TV camera unit is a zoomlens.
 12. A stereoscopic endoscope system according to claim 3 or 4 ,wherein said means for disuniting a plurality of images on a temporalbasis or said means for disuniting a plurality of images on the basis ofpolarization is a means having the ability to change a spectralcharacteristic; such as, a laser beam cutoff ability, infrared cutoffability, or color correction ability.
 13. A stereoscopic endoscopesystem according to claim 1 or 2 , wherein said scope unit and TV cameraunit are turnable relative to each other with the longitudinaldirections thereof as axes.
 14. A stereoscopic endoscope systemaccording to claim 1 or 2 , wherein coupling sections of scope unitsfreely attachable to said TV camera unit have the same shape.
 15. Astereoscopic endoscope system according to claim 8 , wherein saidliquid-crystal shutter is a field-effect liquid-crystal shutter.
 16. Astereoscopic endoscope system according to claim 8 or 15 , wherein saidliquid-crystal shutter is further provided with the capability of adiaphragm.
 17. A stereoscopic endoscope system, comprising: a scope unitincluding an elongated insertion unit that can be inserted in a narrowregion; and a TV camera unit freely attachable to said scope unit,wherein: said scope unit includes an observation optical system having asingle optical axis; said TV camera unit includes a single imageformation optical system, a means for temporally splitting an aperturestop of said image formation optical system, and a single imaging meansfor photoelectrically transferring images formed by said image formationoptical system; and said means for temporally splitting an aperture stopis a means for temporally switching a state, in which one of two areasconstituting said aperture stop of said image formation optical systemis transparent and the other area is interceptive, and a state, in whichsaid one of two areas is interceptive and said the other area istransparent, relative to said two areas constituting said aperture stop.18. A stereoscopic endoscope system according to claim 17 , wherein saidobservation optical system being located in said scope unit and having asingle optical axis is made by arranging an objective optical system,conveying optical system, and eyepiece optical system in that order fromthe object side, and is set to a diopter enabling an image produced bysaid eyepiece optical system to be visually observed.
 19. A stereoscopicendoscope system according to claim 17 , wherein said observationoptical system being located in said scope unit and having a singleoptical axis is made by arranging an objective optical system andconveying optical system in that order from the object side, and a lastimage produced by said conveying image is located in said scope unit.20. A stereoscopic endoscope system according to claim 17 , furthercomprising a rotatable mount mechanism located at a junction betweensaid scope unit and TV camera unit, wherein said insertion unit of saidscope unit can be turned relative to said TV camera unit with respect toan optical axis of said observation optical system in said scope unit asan axis of turning.
 21. A stereoscopic endoscope system according toclaim 17 , wherein said scope unit has a diaphragm having two apertures,which is used to disunite light beams representing right and leftimages, in the vicinity of a position of image formation near a junctionwith said TV camera unit.
 22. A stereoscopic endoscope system accordingto claim 17 , wherein said image formation optical system in said TVcamera unit includes a zooming mechanism.
 23. A stereoscopic endoscopesystem according to claim 17 , wherein said TV camera unit includes amanual focusing mechanism.
 24. A stereoscopic endoscope system accordingto claim 17 , wherein said TV camera unit includes an automatic focusingmechanism.
 25. A stereoscopic endoscope system according to claim 24 ,wherein said automatic focusing mechanism is such that a mismatch in ahorizontal direction between two images extracted separately through twoareas constituting an aperture stop of said image formation opticalsystem is detected substantially in the center of a screen, and at leastpart of said image formation optical system or said imaging means ismoved along an optical axis in order to nullify the mismatch.
 26. Astereoscopic endoscope system according to claim 17 , wherein: said TVcamera unit further includes a coupling section that can be mounted onsaid scope unit having an elongated insertion unit which can be insertedin a narrow region; a single image formation optical system, a means fortemporally splitting an aperture stop of said image formation opticalsystem, and an imaging means for photoelectrically transferring imagesformed by said image formation optical system are incorporated in saidTV camera unit; and said means for temporally splitting an aperture stopis a means for temporally switching a state, in which one of two areasconstituting said aperture stop of said image formation optical systemis transparent and the other area is interceptive, and a state, in whichsaid one of two areas is interceptive and said the other area istransparent, relative to said two areas constituting said aperture stop.27. A stereoscopic endoscope system according to claim 17 , wherein:said TV camera unit further includes a coupling section that can bemounted on said scope unit having an elongated insertion unit which canbe inserted in a narrow region; a single image formation optical system,a means for splitting an aperture stop of said image formation opticalsystem, and an imaging means for photoelectrically transferring imagesformed by said image formation optical system are incorporated in saidTV camera unit; and said means for splitting an aperture stop transmitsa component of light entering one of two areas constituting saidaperture stop of said image formation optical system, which has aspecific nature, and a component of light entering the other area, whichhas a nature different from said specific nature, relative to said twoareas constituting said aperture stop; and said imaging means picks uplight beams transmitted through said two areas.
 28. A TV imaging systemfor an endoscope, comprising: a scope unit having an elongated insertionunit that can be inserted in a narrow region; and a TV camera unit thatcan be mounted on said scope unit, wherein: said TV camera unit includesa single image formation optical system, a means for temporallysplitting an aperture stop of said image formation optical system, andan imaging means for photoelectrically transferring images formed bysaid image formation optical system; and said means for temporallysplitting said aperture stop temporally switches a state, in which oneof two areas constituting said aperture stop of said image formationoptical system is transparent and the other area is interceptive, and astate, in which said one of two areas is interceptive and said the otherarea is transparent, relative to said two areas constituting saidaperture stop.
 29. A TV imaging system for an endoscope, comprising: ascope unit having an elongated insertion unit that can be inserted in anarrow region; and a TV camera unit that can be mounted on said scopeunit, wherein: said TV camera unit includes a single image formationoptical system, a means for temporally splitting an aperture stop ofsaid image formation optical system, and an imaging means forphotoelectrically transferring images formed by said image formationoptical system; said means for temporally splitting an aperture stoptransmits a component of light entering one of two areas constituting anaperture stop of said image formation optical system, which has aspecific nature, and a component of light entering the other area, whichhas a nature different from said specific nature, relative to said twoareas constituting said aperture stop; and said imaging means picks uplight beams transmitted through said two areas.
 30. A stereoscopicendoscope system according to claim 26 or 27 , wherein said TV cameraunit can be mounted on either a three-dimensional scope unit that has anelongated insertion unit which can be inserted in a narrow region andthat emits a plurality of light beams used for three-dimensionalobservation or a single-eye scope unit that has an elongated insertionunit which can be inserted in a narrow region and that emits a singlelight beam used for normal observation.
 31. A TV imaging system for anendoscope according to claim 28 or 29 , wherein said TV camera unit canbe mounted on either a three-dimensional scope unit that has anelongated insertion unit which can be inserted in a narrow region andthat emits a plurality of light beams used for three-dimensionalobservation or a single-eye scope unit that has an elongated insertionunit which can be inserted in a narrow region and that emits a singlelight beam used for normal observation.
 32. A stereoscopic endoscopesystem according to claim 30 , wherein said three-dimensional scope unitincludes a system of objective lenses located in the distal portion ofsaid insertion unit, a system of relay lenses placed coaxially with saidsystem of objective lenses, and a diaphragm means having a plurality ofapertures used to extract a plurality of light beams, which are used toform a plurality of images having a parallax between them, from emittedlight of said system of relay lenses.
 33. A TV imaging system for anendoscope according to claim 31 , wherein said three-dimensional scopeunit includes a system of objective lenses located in the distal portionof said insertion unit, a system of relay lenses located coaxially withsaid system of objective lenses, and a diaphragm means having aplurality of apertures used to extract a plurality of light beams, whichare used to form a plurality of images having a parallax between them,from emitted light of said system of relay lenses.
 34. A stereoscopicendoscope system according to claim 30 , further comprising a pluralityof three-dimensional scope units each including a system of objectivelenses located in the distal portion of said insertion unit, a system ofrelay lenses located coaxially with said system of objective lenses, anda diaphragm means having a plurality of apertures used to extract aplurality of light beams, which are used to form a plurality of imageshaving a parallax between them, from emitted light of said system ofrelay lenses, wherein: a spacing between said plurality of apertures ofsaid diaphragm means in one three-dimensional scope unit is differentfrom a spacing between said plurality of apertures of said diaphragmmeans in any other three-dimensional scope unit.
 35. A TV imaging systemfor an endoscope according to claim 31 , further comprising a pluralityof three-dimensional scope units each including a system of objectivelenses located in the distal portion of said insertion unit, a system ofrelay lenses located coaxially with said system of objective lenses, anda diaphragm means having a plurality of apertures used to extract aplurality of light beams, which are used to form a plurality of imageshaving a parallax between them, from emitted light of said system ofrelay lenses, wherein: a spacing between said plurality of apertures ofsaid diaphragm means in one three-dimensional scope unit is differentfrom a spacing between said plurality of apertures of said diaphragmmeans in any other three-dimensional scope unit.
 36. A stereoscopicendoscope system according to claim 30 , wherein said three-dimensionalscope unit includes a plurality of systems of objective lenses locatedin the distal portion of said insertion unit, and a plurality of systemsof relay lenses located coaxially with said systems of objective lenses.37. A TV imaging system for an endoscope according to claim 31 , whereinsaid three-dimensional scope unit includes a plurality of systems ofobjective lenses located in the distal portion of said insertion unit,and a plurality of systems of relay lenses located coaxially with saidsystems of objective lenses.
 38. A stereoscopic endoscope systemaccording to claim 30 , wherein said three-dimensional scope unitincludes a plurality of systems of objective lenses located in thedistal portion of said insertion unit, and a system of relay lenseswhich is located with their optical axis deviated from those of saidsystems of objective lenses so that light emanating from any of saidplurality of systems of objective lenses can be transmitted, and ofwhich diameter is larger than those of said systems of objective lenses.39. A TV imaging system for an endoscope according to claim 31 , whereinsaid three-dimensional scope unit includes a plurality of systems ofobjective lenses located in the distal portion of said insertion unit,and a system of relay lenses which is located with their optical axisdeviated from those of said systems of objective lenses so that lightemanating from any of said plurality of systems of objective lenses canbe transmitted, and of which diameter is larger than those of saidsystems of objective lenses.
 40. A stereoscopic endoscope systemaccording to claim 30 , wherein said single-eye scope unit includes aplurality of systems of objective lenses that are located in the distalportion of said insertion unit and that permit different field-of-viewdirections, and a system of relay lenses for transmitting lightemanating from said plurality of systems of objective lenses.
 41. A TVimaging system for an endoscope according to claim 31 , wherein saidsingle-eye scope unit includes a plurality of systems of objectivelenses that are located in the distal portion of said insertion unit andthat permit different field-of-view directions, and a system of relaylenses for transmitting light emanating from said plurality of systemsof objective lenses.
 42. A stereoscopic endoscope system according toclaim 27 , wherein said component having a specific nature is a firstpolarized light component of light transmitted through said area, andsaid component having another nature is a second polarized lightcomponent orthogonal to said first polarized light component.
 43. A TVimaging system for an endoscope according to claim 29 , wherein saidcomponent having a specific nature is a first polarized light componentof light transmitted through said area, and said component havinganother nature is a second polarized light component orthogonal to saidfirst polarized light component.
 44. A stereoscopic endoscope systemaccording to claim 42 , wherein said means for disuniting light beams isa polarization beam splitter, and said imaging means includes aplurality of solid-state imaging devices for receiving said first andsecond polarized light components disunited by said polarization beamsplitter.
 45. A TV imaging system for an endoscope according to claim 43, wherein said means for disuniting light beams is a polarization beamsplitter, and said imaging means includes a plurality of solid-stateimaging devices for receiving said first and second polarized lightcomponents disunited by said polarization beam splitter.
 46. Astereoscopic endoscope system according to claim 42 , wherein said meansfor disuniting light beams is a composite polarizer made by juxtaposingnumerous first polarizing devices for intercepting said second polarizedlight component and transmitting said first polarized light componentand numerous second polarizing devices for intercepting said firstpolarized light component and transmitting said second polarized lightcomponent, and said composite polarizer is placed on the incident sideof one imaging device.
 47. A TV imaging system for an endoscopeaccording to claim 43 , wherein said means for disuniting light beams isa composite polarizer made by juxtaposing numerous first polarizingdevices for intercepting said second polarized light component andtransmitting said first polarized light component and numerous secondpolarizing devices for intercepting said first polarized light componentand transmitting said second polarized light component, and saidcomposite polarizer is placed on the incident side of one imagingdevice.
 48. A stereoscopic endoscope system according to claim 26 ,wherein said means for splitting an aperture stop can switch a firststate in which one area containing an optical axis of said imageformation optical system is placed in a transparent state, and a secondstate in which a state in which one of two areas constituting saidaperture stop of said image formation optical system is transparent andthe other area is interceptive, and a state in which said one of twoareas is interceptive and said the other area is transparent areswitched temporally.
 49. A TV imaging system for an endoscope accordingto claim 28 , wherein said means for splitting an aperture stop canswitch a first state in which one area containing an optical axis ofsaid image formation optical system is placed in a transparent state,and a second state in which a state in which one of two areasconstituting said aperture stop of said image formation optical systemis transparent and the other area is interceptive, and a state in whichsaid one of two areas is interceptive and said the other area istransparent are switched temporally.
 50. A stereoscopic endoscope systemaccording to claim 26 or 48 , wherein said means for splitting anaperture stop can vary a spacing between said two areas.
 51. A TVimaging system for an endoscope according to claim 28 or 49 , whereinsaid means for splitting an aperture stop can vary a spacing betweensaid two areas.
 52. A stereoscopic endoscope system according to claim26 or 48 , wherein said means for splitting an aperture stop can varythe orientation of a line linking said two areas.
 53. A TV imagingsystem for an endoscope according to claim 28 or 49 , wherein said meansfor splitting an aperture stop can vary the orientation of a linelinking said two areas.
 54. A stereoscopic endoscope system according toclaim 50 , wherein said means for splitting an aperture stop is aliquid-crystal shutter having a plurality of electrodes locatedconcentrically and a plurality of electrodes located radially, and saidliquid-crystal shutter further includes a driving means for switching aselectively transparent state and an interceptive state relative to anyof areas segmented by said concentric circles and radial lines.
 55. A TVimaging system for an endoscope according to claim 51 , wherein saidmeans for splitting an aperture stop is a liquid-crystal shutter havinga plurality of electrodes located concentrically and a plurality ofelectrodes located radially, and said liquid-crystal shutter furtherincludes a driving means for switching a selectively transparent stateand an interceptive state relative to any of areas segmented by saidconcentric circles and radial lines.